The present invention relates to a connecting structure of a component in a wire harness for selectively assembling a DRL (Daytime Running Light) device to a relay box in a wire harness which is mounted on an automobile.
FIG. 5 shows an example of a related connecting structure of a component in an on-vehicle wire harness.
This on-vehicle wire harness 51 includes a DRL system for lighting headlamps of an automobile at daytime running, for example, in Europe, and is constructed by connecting a secondary relay box 53 for DRL to a primary relay box 52 of the wire harness by a circuit (electric wire). In this specification, the wire harness 51 is described as including both the relay boxes 52 and 53.
In FIG. 5, a circuit from a battery 54 and an ECU (Electronic Control Unit) 57 at a side of a headlamp switch 55 are connected to the primary relay box 52. The secondary relay box 53, and headlamps 58, 60 of low beam are connected to the primary relay box 52 through respective circuits. Further, one of circuits 62 of headlamps 59, 61 of high beam is also connected to the primary relay box 52. The other circuit 63 of the headlamps 59, 61 of the high beam is connected to the secondary relay box 53. The wire harness circuit 51 in FIG. 5 is applied to a case where the headlamps 58 to 61 of four lamp type are employed.
In FIG. 5, denoted by reference numeral 64 is a main fuse at a battery side, 56 is a dimmer switch (a switch for switching between the low beam and the high beam) at a side of the ECU, 65 is a terminal for the headlamps, 66 is a terminal for the DRL, 67 is a relay for the headlamps which is a component in the primary relay box, 68 is a fuse, 69 is a relay for the DRL, 70, 71 are relays for the DRL which are components in the secondary relay box, and 72 is a resistor for the DRL (dimming) which is connected to the secondary relay box 53.
As the on-vehicle wire harness of the type as shown in FIG. 5, a similar structure is disclosed in Patent Document 1, for example. In Patent Document 1, an ignition switch and an output part of engine rotation signals are connected to the DRL control unit (ECU).
FIG. 6 shows an example of a relay box in a related on-vehicle wire harness (Reference should be made to Patent Document 2).
This relay box 81 is arranged at a side of an instrument panel of an automobile. For the purpose of mounting a control unit (not shown) which is a component for DRL together with a relay 82 for supplying power to headlamps, the control unit for the DRL is formed in a substantially same outer shape as the relay 82, and connected to a terminal 84 in a relay connecting cavity (connecting section) 83 in the relay box 81.
The control unit (not shown) for the DRL includes an FET (Field Effect Transistor) acting as a switching element, an IC and a condenser which are mounted on a circuit board and covered with a resin body, having terminals projected from the resin body.
[Patent Document 1] JP-A-2001-1833 (FIG. 1 and FIG. 2)
[Patent Document 2] JP-A-2001-310690 (FIG. 1)
However, in the above described related connecting structure of the component in the on-vehicle wire harness in FIG. 5, the secondary relay box 53, the relays 70, 71, the fuses, connecting circuits (electric wires) 73 and so on have been necessary for achieving the DRL function, which incurs upsizing and complication of the structure. Moreover, the wire harness for the DRL is not compatible with the wire harness in which the DRL system is not required, and hence, two types of the wire harnesses, one for a case having the DRL function, and the other for a case not having the DRL function, are required. Therefore, there has been a problem that high cost is required in production, maintenance, and so on of the wire harnesses.
In the above described related structure of the wire harness including the relay box 81, as shown in FIG. 6, the wire harness can be made compact, because the relay 82 and the DRL device (not shown) which is the control unit for the DRL having the substantially same outer shape as the relay 82 are installed in the relay box 81 at the same time. However, in this structure too, two types of the wire harnesses, specifically, in case where the DRL device is used, and in case where the DRL device is not used, are required. Moreover, in case where a common relay box is used for both the cases, a space for the relay and a space for the DRL device are necessary, because the relay and the DRL device are separately arranged in the relay box. Therefore, there has been such anxiety that the relay box may become large-sized, and the circuit inside the relay box may become complicated.